Switching Combinations on the Fly
Very few keyboards have an effective patch remain feature. Patch Remain means that if I'm playing a note on a string sound with reverb and while holding the note, I switch presets to an electric guitar with distortion, the string sound with reverb should continue to be played until I release it. This is a really nice feature to have during a gig because it means I can make as many preset changes in a single song as I want, and they'll all be made cleanly.
For the rest of us who don't have patch remain on our keyboards, here are some alternatives.
1) Start a song with sounds generated by only one keyboard, then switch to another combi that adds sounds from the second keyboard. A perfect example of this would be the two-preset pad trick I mentioned a couple posts before this one. I could start out without a pad, and add or remove it by changing the combi, since the pad is played on my Korg and the keyboards/organs are played on my Nord. Of course, this means that I'm only adding or removing sounds from one keyboard, so this has a fairly limited purpose.
2) Switch sounds between different keyboards: have one sound played on keyboard A, the next on keyboard B, the next on keyboard A, and so on. As long as the delay on the keyboard you're playing on is minimal, or you actually move your hand to a different keyboard as you switch the sound, there won't be any delay in the notes.
3) If one of your keyboards lets you set individual timbres to ignore control changes, you can set some to ignore CCs and some not to, and use an expression pedal sending CC #7 (Volume) to add or remove the new voices. You might even be able to have a setup where some voices respond to CC#7 in reverse, so you can both add and remove voices at the same time. The trick is to remember that when you switch to this combi, the volumes of the voices probably *won't* be affected by the initial position of the pedal, so even though the pedal may be fully closed, those voices would still sound. To get around this, you could push the pedal down with your toe a bit and then back with your heel; the change in position would get the keybaord to notice the pedal position. Alternately, depending on how CC#7 works on your keyboard, you could set some voices to volume 0 and save them in the combi; this might lose the balance between voices though, so pushing the pedal all the way up might put all voices at full volume, which might not be what you want.
You can accomplish this on a Korg keyboard by checking/unchecking the "Other CCs" checkbox for a timbre. On the Korg TR, this is found on the MIDI4 page, on the second tab. Anything checked off is affected by the position of the expression pedal; anything not checked off will always be on. By default, an expression pedal connected to the Korg TR will send CC #7.
4) If you have hardware buttons to mute or unmute voices, use those. Even better if you can easily assign one button to mute and/or unmute multiple voices at once. Better still if you have several buttons to do so.
5) If you own a Motif-derived keyboard (including the MO), your 16-part multitimbral mode is Song Mode (somewhat unintuitive, since the same mode for sequencing songs is used for live playback!) Songs and patterns have 5
scenes, each of which is a full capture of the mix settings for all songs. You can't change timbres between scenes, but you can mute some parts in one scene and not in another. There are 5 hardware buttons to switch between scenes.
6) Start/stop transmission on a MIDI channel. In my setup, if I want to play a sound on the Korg while playing on the keybed of my Nord, I have an Extern section active. I can turn this on and off with a single toggle button, so I can easily disable timbres on the Korg from sounding because they won't be receiving the note on/note off messages (or anything else).
7) For Korg users,
here are three alternate ways of switching voices on and off in a combi. The first requires modifying individual programs so they respond to one of the two hardware switches by changing their volume. The second involves using a limiter in an effects slot so that when the limiter is activated, some sounds are muted or unmuted, and the third (Korg M3 only), is to use the Karma On/Off switch to mute or unmute parts.